Short-term effects of organo-mineral enriched biochar fertiliser on ginger yield and nutrient cycling

Purpose

Biochar has agronomic potential but currently is too expensive for widespread adoption. New methodologies are emerging to reduce the cost such as enriching biochar with nutrients that match crops and soil requirements. However, the effects of biochar-based fertilisers on plant yield and soil nutrient availability have not been widely examined. This study investigated the effects of a novel organo-mineral biochar fertiliser in comparison to organic and commercial biochar fertiliser on ginger (Zingiber officinale Canton).

Materials and methods

There were four treatments: (1) commercial organic fertiliser (5 t ha^?1), as the control; (2) commercial biochar-based fertiliser (5 t ha^?1); (3) organo-mineral biochar fertiliser at low rate (3 t ha^?1); and (4) organo-mineral biochar fertiliser at high rate (7.5 t ha^?1). A replicated pot trial was established with black dermosol soil and ten replicate pots for each treatment. Ginger was planted and grown for 30 weeks. Plant growth, biomass, foliar nutrients and water extractable soil nutrients including phosphorus (P), potassium (K) and calcium (Ca) were examined.

Results and discussion

High rate organo-mineral biochar fertiliser increased soil P and K availability at week 30 (harvest) after planting, compared to all other treatments and low rate organo-mineral biochar fertiliser performed similarly to the organic control for P and K. High rate organo-mineral biochar fertiliser increased total foliar nutrient content at week 30 in P, K and Ca compared to commercial biochar fertiliser. High rate organo-mineral biochar fertiliser improved the commercial value of ginger (+?36%) due to a shift in the proportion of higher grade rhizomes. Low rate organo-mineral biochar fertiliser plants displayed similar yield, total dry and aboveground biomass to commercial organic fertiliser. Commercial biochar fertiliser had significantly lower biomass measures compared with other treatments as the rate applied had lower nutrient concentrations.

Conclusions

Our results show organo-mineral biochar fertilisers could be substituted for commercial organic fertilisers at low rates to maintain similar yield or applied at high rates to increase commercial value where economically feasible.

     

Composition of turfgrass thatch

Abstract

In many intensively cultured turfs, thatch, an organic layer of leaves, stems, and roots, that develops above the soil surface, is recognized as a potentially serious problem. This study evaluated the constituents of turfgrass thatch in terms of organic matter (OM), cellulose, and lignin content. Ten samples were analyzed containing two or three layers of 2‐cm thick for a total of 30 layers. As thatch layers may often include mineral matter, a technique was developed to separate the OM from any mineral particles in the samples. An important loss of OM was observed during the separation process. Despite problems encountered during the constituent analyses due to the heterogeneity of the samples and the presence of mineral matter, results showed a significant increase in lignin content with depth.     

Suspended matter and associated contaminants in Danish streams: a national analysis

Purpose

Suspended matter (SM) in streams is usually considered of minor importance in Danish environmental management. However, SM has some ecological effects as it may (1) clog fish spawning grounds and (2) act as an important agent for transport and exposure of biota to chemical substances, such as phosphorus and toxic inorganic (e.g. heavy metals) and organic (e.g. pesticides) substances.

Materials and methods

A large national data set of >?100,000 water samples analysed for SM and loss on ignition was investigated for spatial concentration patterns, sediment yields and temporal trends. Moreover, the importance of SM as a transport agent for phosphorus and heavy metals in streams was investigated through a correlation analysis.

Results and discussion

The mean suspended matter concentration (SMC) (including organic matter) amounted to 12 mg l^?1, with an organic content of 4.9 mg l^?1 (41%). A clear difference in SMC temporal trends over the sampling period was found between geographical regions. Sediment yields were calculated for all major catchments revealing low sediment yields (1–15 t km^?2 year^?1) compared to neighbouring countries and showed clear geographical patterns. Statistically significant relationships were established between SMCs, suspended sediment concentrations (SSCs) (excluding organic matter) and organic matter concentrations (OMCs) and particulate phosphorus (PP) concentrations, and again spatial patterns appeared. However, it was clearly shown that SMC/SSC/OMC could not be used as a robust, nationwide, indicator for PP concentrations. Analyses of the relationship between SMC and particle-bound heavy metal concentrations generally revealed weak correlations except for Pb and Ni (median R²?>?0.3).

Conclusions

Relatively low SM concentrations and sediment yields were found. SM is, in some geographical regions, an important transport agent for PP. Clear geographical patterns occurred in the relationships between SMC/SSC/OMC and both river water discharge and PP, as well as for sediment yields and for temporal trends in SMC.

     

Contrasting composition of free and mineral-bound organic matter in top- and subsoil horizons of Andosols

Andosols are characterised by high organic matter (OM) content throughout the soil profile, which is mainly due to the stabilisation of soil organic matter (SOM) by mineral interactions. The aim of the study was to examine whether there were differences in the chemical composition of mineral-associated SOM and free OM in the top A horizon and in the subsoil (horizons below the A11 horizon). Our experimental approach included the replicated sampling of a fulvic and an umbic Andosol under pine and laurel forest located on the island of Tenerife with a Mediterranean sub-humid climate. We determined the extent of the organo-mineral interactions by comparing the sizes of the light (free) and heavy (dense) soil fractions obtained by physical separation through flotation in a liquid with a density of 1.9 g cm^–3. We determined the elemental and isotopic composition of both fractions and analysed their chemical composition by analytical pyrolysis. The elemental and isotopic composition showed similar values with depth despite the different vegetation and climatic conditions prevailing at the two sites. Carbon (C) stabilised by mineral interactions increased with depth and represented 80–90% of the total C in the lowest horizons. The heavy fractions mainly released N-containing compounds upon analytical pyrolysis, whereas lignin-derived and alkyl compounds were the principal pyrolysis products released from the light fractions of the top- and subsoil horizons. Principal component analysis showed that the chemical composition of OM stabilised by mineral interaction differs in the different horizons of the soil profile. In the A horizons, the chemical composition of this OM was similar to those of the light fractions, i.e. litter input. There was a gradual change in the bulk molecular composition from a higher contribution of plant-derived molecules in the light and heavy fractions of the A horizon to more microbial-derived molecules as well as black C-derived molecules at depth. We conclude that transport processes in addition to decomposition and possibly in situ ageing affect the chemical composition of mineral-associated OM in subsoils.     

Size fractions of organic matter pools influence their stability: Application of the Rock-Eval® analysis to beech forest soils

Soil organic matter (SOM) is a complex heterogeneous mixture formed through decomposition and organo-mineral interactions, and characterization of its composition and biogeochemical stability is challenging. From this perspective, Rock-Eval^® is a rapid and efficient thermal analytical method that combines the quantitative and qualitative information of SOM, including several parameters related to thermal stability. This approach has already been used to monitor changes in organic matter (OM) properties at the landscape, cropland, and soil profile scales. This study was aimed to assess the stability of SOM pools by characterizing the grain size fractions from forest litters and topsoils using Rock-Eval^® thermal analysis. Litter (organic) and topsoil samples were collected from a beech forest in Normandy (France), whose management in the last 200 years has been documented. Fractionation by wet sieving was used to separate large debris (> 2 000 μm) and coarse (200-2 000 μm) and fine particulate OM (POM) (50-200 μm) in the organic samples as well as coarse (200-2 000 μm), medium (50-200 μm), and fine (< 50 μm) fractions of the topsoil samples. Rock-Eval^® was able to provide thermal parameters sensitive enough to study fine-scale soil processes. In the organic layers, quantitative and qualitative changes were explained by the progressive decomposition of labile organic compounds from plant debris to the finest organic particles. Meanwhile, the grain size fractions of topsoils presented different characteristics. The coarse organo-mineral fractions showed higher C contents, albeit with a different composition, higher thermal stability, and greater decomposition degree than the plant debris forming the organic layer. These results are consistent with those of previous studies that microbial activity is more effective in this fraction. The finest fractions of topsoils showed low C contents, the highest thermal stability, and low decomposition degree, which can be explained by the stronger interactions with the mineral matrix. Therefore, it is suggested that the dynamics of OM in the different size fractions be interpreted in the light of a plant-microbe-soil continuum. Finally, three distinct thermostable C pools were highlighted through the grain size heterogeneity of SOM:free coarse OM (large debris and coarse and fine particles), weakly protected OM in (bio)aggregates (coarse fraction of topsoil), and stabilized OM in the fine fractions of topsoil, which resulted from the interactions within organo-mineral complexes. Therefore, Rock-Eval^® thermal parameters can be used to empirically illustrate the conceptual models emphasizing the roles of drivers played by the gradual decomposition and protection of the most thermally labile organic constituents.     

Linear Regression Models to Estimate Exchangeable Sodium Percentage and Bulk Density of Salt Affected Soils in Sahl El-Hossinia,El-Sharkia Governorate,Egypt

ABSTRACT

The objective of this study was to develop a Linear Regression Model for the prediction of soil bulk density based on organic matter content (OM) and textural fractions (% sand, silt and clay) as well as the soil exchangeable sodium percentage (ESP) based on soil sodium adsorption ratio (SAR) in some salt affected soils of Sahl El-Hossinia, El-Sharkia Governorate, Egypt. For this purpose, 160 samples were randomly taken from top of the surface soil (0–30 cm) from different locations and samples were subjected to various analyzes. XLSTAT Version 2016.02.27444 software was used to build and test conceptual and empirical models. The statistical results of the study indicated that to predict soil bulk density (BD) based on organic matter content and textural fractions the Multiple linear regression model BD = 1.817–0.730 × OM – 0.002 × Clay – 0.001 × Silt with R² = 0.794. On the other hand, to predict soil ESP based on SAR the linear regression model ESP = 5.577 + 0.851 × SAR with R² = 0.773. A Linear Regression Model for prediction of BD and ESP of Sahl El-Hossinia, El-Sharkia Governorate, Egypt, can be used with high prediction.     

An assessment of the concentrations of PCDDs/Fs in contaminated bottom sediments and their sources and ecological risk

Purpose

The purpose of the study was to determine the levels of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F), two types of persistent organic pollutant (POP), in an urban retention reservoir located in an industrial zone within a coal-mining region. It also assesses the potential ecological risk of the PCDDs/Fs present in bottom sediments and the relationship between their content and the fraction of organic matter.

Materials and methods

The sediment samples were collected from Rybnik Reservoir, located in the centre of the Rybnik Coal Region, Silesia, one of Poland’s major industrial centres. Seventeen PCDD/F congeners in the surface of the sediments were analysed using high-resolution gas chromatography and high-resolution mass spectrometry (HRGC/HRMS).

Results and discussion

The toxic equivalency (TEQ) of the PCDDs/Fs in the sediments ranged from 1.65 to 32.68 pg TEQ g^?1. PCDDs constituted 59–78% of the total PCDDs/Fs, while the PCDFs accounted for 22–41%. The pattern of PCDD/F congeners in the sediments was dominated by OCDD. However, the second-most prevalent constituents were OCDF and ∑HpCDFs in the low TOC sediment (< 10 g TOC kg^?1), but HpCDD in the rich TOC samples (> 10 g TOC kg^?1). PCDD/F concentrations in the sediment samples were 2- to 38-fold higher than the sediment quality guidelines limit, indicating high ecological risk potential. Although a considerable proportion of PCDDs/Fs in the bottom sediments from the Rybnik Reservoir were derived from combustion processes, they were also obtained via transport, wastewater discharge, high-temperature processes and thermal electricity generation. The PCDD/F concentrations were significantly correlated with all fractions of organic matter; however, the strongest correlation coefficients were found between PCDDs/Fs and humic substances. Besides organic matter, the proportions of silt/clay fractions within sediments played an important role in the transport of PCDDs/Fs in bottom sediments.

Conclusions

The silt/clay fraction of the bottom sediments plays a dominant role in the movement of PCDDs/Fs, while the organic matter fraction affects their sorption. The results indicate that the environmental behaviour of PCDDs/Fs is affected by the quantity and quality of organic matter and the texture of sediments.

     

Chemical contamination in upper horizon of Haplic Chernozem as a transformation factor of its physicochemical properties

Purpose

The effect of Cu, Zn, and Pb high rates on the physical properties and organic matter of Haplic Chernozem (Clayic) (A1 horizon 0–20 cm) under model experimental conditions was studied.

Materials and methods

In a model experiment, soil samples of Haplic Chernozem (Clayic) were artificially contaminated with 2000 mg/kg of Cu, Zn, and Pb acetates added separately. The particle-size fraction, the microaggregates distribution, the structural status, the total content and fractional and group composition of organic matter, physico-mechanical properties were determined in soil without metals and soil contaminated with metals.

Results and discussion

At the soil contamination with Cu, Zn, and Pb, the content of organo-mineral colloids increased, which results to the increasing of the clay fraction content by 4.5% compared to the control. The analysis of the microaggregate size composition of the studied soil shows that the content of coarser aggregates (1–0.25 mm) increases and the content of finer (0.05–0.001 mm) aggregates decreases after the addition of HMs and correspond to the HMs series: Cu → Zn → Pb. A significant decrease in the coefficient of water stability in the control from 3.0 to 1.4–1.5 in the contaminated treatments. The structural status (estimated from total agronomically valuable aggregates) changes from excellent to good. The addition of Cu, Zn, and Pb to the soil affects the quantitative composition of organic matter. The contents of free and sesquioxide-bound humic acids and free fulvic acids increased. The contamination with Zn and Pb causes the aliphatization of organic matter.

Conclusions

Under conditions of model experiment, the contamination of Haplic Chernozem (Clayic) with high rates of Cu, Zn, and Pb leads to changes of the microaggregates distribution, the structural status, and the qualitative composition of organic matter.

     

Influence of Long-Term Localized Fertilizer Applications on Soil Organo-Mineral Complexes in a Sheltered Vegetable Field

Organo-mineral interactions are considered to play a relevant role in organic matter (OM) protection against biodegradation in regard to soil developed under sheltered vegetable conditions. However, little is known about the effect of fertilizer applications on the composition of organo-mineral interactions. A long-term (16 years) fertilizer experiment was carried out in a sheltered vegetable field at Shenyang Agricultural University, Shenyang, China, in order to study the effects of different fertilizer applications on organo-mineral complexes. It was found that a long-term application of a combination of organic plus chemical fertilizers induced a higher concentration of OM than applying chemical fertilizers alone, and loosely bound humic (LB-H) slightly increased with application of a combination of organic and chemical fertilizers. No significant influence on firmly bound humic (FB-H) was found among the chemical fertilizer treatments, whereas the application of organic fertilizer slightly decreased the content of FB-H compared to chemical fertilizer treatments. More tightly bound humic (TB-H) was observed in organic fertilizer treatments than in chemical fertilizer treatments, and its highest concentration (11.53 g kg^?1) was in the treatment of organic fertilizer plus nitrogen (N)-phosphorus (P)-potassium (K) chemical fertilizers. The ratio of LB-H/TB-H tended to decrease after a long-term application of organic fertilizer, being the lowest (1.10) in the treatment of organic fertilizer plus P-K chemical fertilizer.     

Soil proprieties and alfalfa (Medicago sativa L.) responses to sustainable treated urban wastewater reuse

ABSTRACT

The present work aims to perform an experimental reuse study of raw and sustainable treated urban wastewaters in the irrigation of alfalfa (Medicago sativa L.) under semi-controlled conditions. The obtained results highlight a significant effect (p < 0.05) of water quality on soil monitored parameters. Compared to control soils irrigated with groundwater (GW), those irrigated with treated urban wastewaters from the modified activated sludge process (PTW) and raw urban wastewater (RW) showed significant increase in their organic matter (OM) and nutrients content. Indeed, in comparison to GW organic matter (OM) of RW and PTW was 5,37 and 3,84 times higher; Kjeldahl nitrogen (TKN) was 3,50 and 2,81 times higher and total phosphorus (TP) was 4,00 and 3,25 times higher, respectively. The results showed also a significant effect of water quality on yield, macro and microelements concentrations of alfalfa plant. Hence, the highest yield, macro and microelements uptake of the plant were obtained in response to irrigation with PTW and RW compared to control soil GW. Concerning trace metallic elements concentrations, pots irrigated with RW and PTW showed relatively higher concentrations than those of GW pots.     

Effects of iron,calcium, and organic matter on phosphorus behavior in fluvo-aquic soil: farmland investigation and aging experiments

Purpose

Excessive fertilization has led to a high risk of phosphorus (P) leaching and related problems in the North China Plain, where the most typical cropland soil is fluvo-aquic soil. The main factors controlling environmental P behavior and the acting time sequence of these factors in soil after long-term P fertilizer application have not been well recognized. A clear understanding is essential for effective P management.

Materials and methods

Effects of Fe minerals, calcium carbonate, and organic matter (OM) on P immobilization in fluvo-aquic soil were studied systematically through farmland investigation and aging experiments.

Results and discussion

Phosphorus associated with Ca was the primary fraction in fluvo-aquic soil. Even though there was no significant correlation between the total contents of P and Ca in soils, formation of P-Ca phases facilitated by Ca²⁺ in soil solution was a mechanism of P retention when soil received excess P fertilizer. Positive correlations between the contents of P and Fe and total organic carbon (TOC) indicate that Fe minerals and OM have significant effects on P immobilization. Through the aging experiments, P was found to primarily adsorb on goethite and gradually forms Ca-P compounds. Organic fertilizer caused P release and inhibition of P adsorption in the initial stages; however, OM derived from organic fertilizer might facilitate P immobilization in the long term through the formation of a P-Ca-OM complex.

Conclusions

Although superfluous application of P fertilizers leads to the gradual formation of Ca-P in fluvo-aquic soils, there is still a risk of P loss because P is not immediately adsorbed by Fe minerals. Moreover, application of organic fertilizers increases the risk of P loss. These results provide an important scientific basis for initiating P management policies for fluvo-aquic soils.

     

Distribution characteristics of iron,carbon, nitrogen and phosphorus in the surface soils of different land use types near Xingkai Lake

Purpose

The purpose of this study was to research the differences in iron, phosphorus, nitrogen and organic matter contents at two soil depths in areas with different land use types in the Xingkai Lake National Nature Reserve and to determine the causes of those differences. Additionally, this study sought to analyse the correlations between the contents of different nutrients and to determine the reasons for those correlations.

Materials and methods

Five typical land use types, namely, lakeshore sandy land, grassland, forestland, dryland and wetland, were selected in the Xingkai Lake National Nature Reserve. The contents of amorphous iron (Fe_o), complexed iron (Fe_p), dithionite-extractable iron (Fe_d), total iron (TFe), total phosphorus (TP), total nitrogen (TN) and organic matter (OM) were measured in these soils at two depths: 0–5 cm (soil depth 1) and 5–10 cm (soil depth 2).

Results and discussion

For soil depth 1 and soil depth 2, the land use type had no significant effect on the element contents. For the entire soil depth range (0–10 cm), the land use type had the most significant impact on the TP content (p?<?0.01). Furthermore, soil depth had a significant effect on the contents of Fe_o (p?<?0.01), TP (p?<?0.01) and OM (p?<?0.05). Overall, the element content at soil depth 2 was higher than that at soil depth 1. The interaction between land use type and soil depth significantly influenced the contents of TN and OM (p?<?0.05). The contents of TN and OM in the lakeshore sandy land and dryland were high, and the contents of TN and OM were highly positively correlated (r?=?0.90652, p?<?0.01).

Conclusions

Different land use types caused different degrees of disturbance in the soil, resulting in differences in the element contents in the soils. The differences in the distribution of soil element contents in the topsoil were the result of important natural and human factors.

     

The source and diagenesis of sediment organic matter in the upper Pearl River Estuary as indicated by amino sugars

Purpose

The source and diagenesis of sediment organic matter (OM) based on amino sugar yields and compositions were investigated in sediment samples collected along a reach of the upper Pearl River Estuary in south China.

Materials and methods

Sediment samples were collected from the estuary. Three sediment size fractions—coarse particulate OM (CPOM), fine particulate OM (FPOM), and ultrafiltered dissolved OM (UDOM)—were analyzed for total hydrolysable amino sugars (THAS), total organic carbon (TOC), and total nitrogen (N).

Results and discussion

THAS contributed much more to sediment TOC and total N in UDOM than in CPOM and FPOM. Percentages of TOC as THAS increased with increasing sediment size. The low glucosamine/galactosamine ratios indicated a relatively large bacterial contribution to the sediment OM size fractions and the less reactive nature of sediment OM in the upper Pearl River Estuary. However, the depletion in muramic acid in the three sediment fractions, especially in UDOM, suggested that living bacteria or intact peptidoglycan units were not a major contributor to sediment OM.

Conclusions

The increases of TOC as THAS and C-normalized yields of THAS with the different sediment size fractions demonstrated that they could be used as diagenetic indicators.     

Analysis of bacterial communities on alkaline phosphatase genes in soil supplied with organic matter

Abstract

We studied the effects of the application of organic matter (OM) and chemical fertilizer (CF) on soil alkaline phosphatase (ALP) activity and ALP-harboring bacterial communities in the rhizosphere and bulk soil in an experimental lettuce field in Hokkaido, Japan. The ALP activity was higher in soils with OM than in soils with CF, and activity was higher in the rhizosphere for OM than in the bulk soil. Biomass P and available P in the soil were positively related to the ALP activity of the soil. As a result, the P concentration of lettuce was higher in OM soil than in CF soil. We analyzed the ALP-harboring bacterial communities using polymerase chain reaction based denaturing gradient gel electrophoresis (DGGE) on the ALP genes. Numerous ALP genes were detected in the DGGE profile, regardless of sampling time, fertilizer treatment or sampled soil area, which indicated a large diversity in ALP-harboring bacteria in the soil. Several ALP gene fragments were closely related to the ALP genes of Mesorhizobium loti and Pseudomonas fluorescens. The community structures of the ALP-harboring bacteria were assessed using principal component analysis of the DGGE profiles. Fertilizer treatment and sampled soil area significantly affected the community structures of ALP-harboring bacteria. As the DGGE bands contributing to the principal component were different from sampling time, it is suggested that the major bacteria harboring the ALP gene shifted. Furthermore, there was, in part, a significant correlation between ALP activity and the community structure of the ALP-harboring bacteria. These results raise the possibility that different ALP-harboring bacteria release different amounts and/or activity of ALP, and that the structure of ALP-harboring bacterial communities may play a major role in determining overall soil ALP activity.     

Determination of organic matter content in arid‐zone soils using a simple “loss‐on‐ignition” method

Abstract

A simple and rapid procedure for the determination of organic matter content in mineral soils by loss‐on‐ignition without pretreatment was studied. Attention was given to the possible effect of inorganic compounds abundant in mineral soils on the estimation of organic matter content by this method. Both fast heating (DTA‐TGA type) studies and prolonged heating procedures were employed on natural and “synthetic”; soils. The results were compared to those obtained by the dichromate wet‐oxidation method widely used in soil laboratories for organic matter determination. In a group of 91 soils collected from various mineral soils in Israel, and having OM contents between 0.09 and 13.23%, a correlation coefficient of 0.972 was obtained for the linear regression between organic matter content measured by the proposed method and organic carbon measured by the dichromate wet‐oxidation method.     

Evaluation of organic matter stabilization in sewage sludge

Abstract

The ratio between non‐humified and humified fractions in pyrophosphate extracts is shown to vary during maturation of sewage sludge. The ratio is higher than 1 in the raw materials but lowers at 1 or less than 1 with the aging of sludge and is assumed to reflect quantitatively the degree of stabilization of organic matter in the sludge. Analytical isoelectrofocusing (IEF) experiments showed that humified fractions in raw sludge focalize only in the pH gradient regions lower than 5.0, whilst in older sludge samples a progressive strengthening of bands occurs in the region between pH 6.5 and 5.0, approaching at least partially IEF patterns of soil organic matter. IEF patterns are suggested to reflect the stabilization of organic matter in sewage sludge from a qualitative point of view.     

食用菌栽培对棉籽壳营养价值及山羊瘤胃动态降解率的影响

为了研究4种食用菌栽培后对栽培基质棉籽壳的营养价值和山羊瘤胃动态降解率的影响,选用6只年龄(10月龄)、体重[(35.42±3.96)kg]接近并装有永久瘤胃瘘管的槐山羊羯羊,通过化学分析法测定了棉籽壳和4种菌糠的化学成分,并采用尼龙袋技术,分5批次测定了棉籽壳、平菇菌糠、木耳菌糠、金针菇菌糠和白灵菇菌糠瘤胃动态降解率。结果表明:(1)4种菌糠干物质(DM)和有机物(OM)含量分别比其栽培原料棉籽壳的含量降低13.09%~19.67%(P<0.01)和14.13%~39.52%(P<0.01),粗蛋白(CP)含量分别比棉籽壳提高40.20%~34.29%(P<0.01),中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量分别比棉籽壳降低3.07%~39.72%和17.80%~45.91%(P<0.01);(2)木耳菌糠、金针菇菌糠、白灵菇菌糠的DM和OM在瘤胃内的有效降解率和a+b值(快速降解部分和慢速降解部分之和)均极显著高于棉籽壳(P<0.01),平菇菌糠的DM和OM在瘤胃内的有效降解率显著高于棉籽壳(P<0.05);平菇菌糠、金针菇菌糠、白灵菇菌糠的CP在瘤胃内的有效降解率和a+b值均极显著高于棉籽壳(P<0.01);4种菌糠的NDF和ADF在瘤胃内的有效降解率分别比棉籽壳提高76.72%~702.63%(P<0.01)和137.41%~575.31%(P<0.01)。因此,在棉籽壳上栽培4种食用菌均能改善棉籽壳的营养价值和提高山羊瘤胃消化率,栽培食用菌后的菌糠更有利于作为反刍动物饲料进行利用。     

The Influence of pH and Organic Matter from Sugarcane By-products on Soil Cadmium Fractionation

ABSTRACT

Crop wastes or by-products can have the potential to be used as effective amendments to improve agricultural soil quality and/or crop yields subject to appropriate screening and testing. Sugarcane (Saccharum officinarum L.) waste by-products from an ethanol production plant, including boiler ash, filter cake, and vinasse, were applied as soil amendments at 5%, 10%, 20%, and 40% (w/w) to study the relationship between pH and organic matter (OM) on cadmium (Cd) bioavailability and adsorption via organic matter using the Cd sequential extraction procedure. Soil pH was significantly affected by aging of the treatment with boiler ash, filter cake, and vinasse. At the end of the experiment, the Cd concentrations with all treatments were mainly released in the first two extraction steps of the sequential procedure, i.e., most mobile and easily mobilized fractions. Pearson correlation analyses revealed a negative relationship between pH and bioavailable Cd and between OM and oxidizable Cd. The pH reduction induced by the amendments was a major factor affecting soil Cd bioavailability. The effect of OM on Cd fractionation could not be clearly observed and interpreted in this study.     

Kinetics and Adsorption Isotherms of Bisphenol A, Estrone, 17β-Estradiol, and 17α-Ethinylestradiol in Tropical Sediment Samples

The sorption of four endocrine disruptors, bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) in tropical sediment samples was studied in batch mode under different conditions of pH, time, and sediment amount. Data obtained from sorption experiments using the endocrine disruptors (EDs) and sediments containing different amounts of organic matter showed that there was a greater interaction between the EDs and organic matter (OM) present in the sediment, particularly at lower pH values. The pseudosecond order kinetics model successfully explained the interaction between the EDs and the sediment samples. The theoretical and experimentally obtained q _e values were similar, and k values were smaller for higher SOM contents. The k _F values, obtained from the Freundlich isotherms, varied in the ranges 4.2–7.4 × 10⁻² (higher OM sediment sample, S₂) and 1.7 × 10⁻³–3.1 × 10⁻² (lower OM sediment sample, S₁), the latter case indicating an interaction with the sediment that increased in the order: EE2 > > E2 > E1 > BPA. These results demonstrate that the availability of endocrine disruptors may be directly related to the presence of organic material in sediment samples. Studies of this kind provide an important means of understanding the mobility, transport, and/or reactivity of this type of emergent contaminant in aquatic systems.     

Using a mixture of microalgae,biochar, and organic manure to increase the capacity of soil to act as carbon sink

Purpose

Microalgae, biochar, or organic manure (OM) can be used as soil amendments to enhance soil organic carbon (OC) content. In the present study, a mixture of all three was used to test whether they could further improve soil OC content and the soil’s ability to retain and fix carbon.

Materials and methods

A laboratory incubation study was carried out to evaluate the efficacy of using microalgae, biochar, OM, or their mixture, as a soil amendment to improve OC in soil extract. Metabolic processes and soil microbial community structuring were analyzed to explore the mechanism by which the mixture increased the capacity of soil to act as a carbon sink.

Results and discussion

OC increased markedly (2.9 times its initial level) following the amendment of the soil with a treatment comprising microalgae, biochar, and the highest dose of OM. Microalgal metabolites were utilized by soil microorganisms as a carbon source. Biochar reduced the concentration of extracellular polysaccharides, whereas OM increased extracellular protein concentration. These metabolites affected the relative proportions of different groups of soil microorganisms, thereby increasing the proportion of Rhodobacter and Runella, which exerted a positive synergistic effect on soil OC and increased the soil’s capacity to fix carbon.

Conclusions

A mixture including microalga, biochar, and OM as a soil amendment improved the OC of soil extract, and its effect was greater than that of any of its components alone. The findings of this study can help in devising ways to increase the OC content and the CO₂-fixing capacity of the soil.